High-speed rotative arc welding device

ABSTRACT

This invention relates to a rotational arc welding machine that gives a rotational circular motion to arc generated from an electrode. The machine supports rotatably an electrode (20) at a predetermined distance (d) from the center of a disc (25) which makes a rotational circular motion and at the same time supports said electrode at the upper part thereof as the supporting point therefor, causing the arc generated from said electrode to make a rotational circular motion by rotating said disc. Accordingly, in the said machine, even though the lower part of the electrode makes a circular motion, the electrode itself does not rotate; therefore, electricity can be directly supplied to the electrode.

TECHNICAL FIELD

This invention relates to a high-speed transfer arc welding device forperforming a welding operation while causing a high-speed rotation ofthe welding arc.

BACKGROUND ART

The present inventors have proposed a rotative arc welding device(Japanese laid-Open Publication No. 58-176073) which has given rise tomany useful results by application to a narrow-groove welding. Accordingto this welding device, the high-speed rotation of the welding arcpromotes penetration at the side wall of the groove while also producinga concave bead shape suitable for multi-layer welding. The result is thesignificantly improved quality of the narrow groove welding. Thiswelding device is hereafter referred to as the conventional weldingdevice.

This conventional welding device has a vertically oriented rotary nozzleto the end of which is attached a tip having a wire supply openingoffset from the axis outwardly, a power receiving plate secured to theupper end of the rotary nozzle and having a center wire insertingopening, a carbon brush the lower surface of which slides on the uppersurface of said power receiving plate, a power supply plate secured tothe upper surface of said carbon brush, and a wire inlet the lower endof which is passed through said power supply plate and said carbon brushso as to face to the upper surface of the wire inserting opening in saidpower receiving plate and having a wire insertion opening at the centerattached to a supporting arm in turn extended from the main body of thedevice. The conventional welding device further includes a guide rod,the lower end of which is suspendedly mounted to said supporting arm isfitted into guide apertures in the power supply plate and in the carbonbrush, a resilient member for pressing towards the power receiving platethe carbon brush which is fitted to the periphery of the guide rod andcarrying the power supply plate, a wire feeder for feeding the weldingwire through the wire inlet to the rotary nozzle, and a pair of shieldgas nozzles provided on both sides of the rotative nozzle with its openside directing towards the end of the rotative nozzle.

The welding device of this type is shown schematically in FIG. 2. In thedrawing, the numeral 1 denotes a gear box, the numeral 2 an electricmotor, the numeral 3 an electrode, the npmeral 4 a wire inlet, thenumeral 5 a shield gas nozzle base block, the numeral 6 a shield gasnozzle, the numeral 7 a wire feeder, the numeral 8 a welding wire, thenumeral 9 a roller, the numeral 10 a wire feeding electric motor, thenumeral 11 a power receiving plate, the numeral 12 a carbon brush, thenumeral 13 a power supplying plate, the numeral 14 a guide plate, thenumeral 15 a guide rod, the numeral 15 a spring, the numeral 16 a powersupply cable, the numeral 17 a current supply cable terminal attachmentopening, the numeral 18 a supporting arm and the numeral 19 a rotarypostion sensor.

The above described welding device makes use of the carbon brush 12 forpower supply since the electrode 3 itself is rotated. Thus the contactarea for the carbon brush 12 must be procured for assuring a currentsupply capacity, while the rotative contact resistance of the carbonbrush 12 need be considered, so that the current supply section or theelectrical motor 2 is necessarily increased in size. This, however, hasproved to be a hindrance when it is required to reduce the size of thewelding device.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a high speedrotative arc welding device in which the rotative system for theelectrode is improved in order to provide for reduction in size andweight without sacrificing the advantages of the prior-art weldingdevice.

According to the high-speed rotative arc welding device of the presentinvention, the electrode is rotatively supported with an offset of apredetermined distance from the center of a disk performing a rotativemovement, and the disk is driven into rotation with the upper portion ofthe electrode as the supporting point, so that the arc emitted by theelectrode is caused to perform a rotative circular movement.

In such manner, in accordance with the present invention, the electrodeitself is not rotated when the lower end of the electrode performs acircular movement. It is therefore possible to supply the power directlyto the electrode.

Therefore, with the high-speed rotative arc welding device of thepresent invention, as compared with the conventional rotative arcwelding device, the following outstanding results may be achieved.

(a) In the conventional welding device, the space for the supply sectionis increased, because the power supply is through a contact power supplysystem with the aid of a carbon brush. On the other hand, a large-sizedrotating electrical motor is required because of the contact resistanceof the carbon brush.

Conversely, in the welding device of the present invention, since thepower can be supplied directly to the electrode nozzle, the spacenecessary for the power supply section is considerably reduced. Also,since there is no contact resistance of the carbon brush, a small-sizedelectric motor can be used more extensively than heretofore so that thewelding device may be significantly reduced in size and weight.

(b) In the conventional welding device, the electrode itself is driveninto rotation. In the welding device of the present invention, it isonly the lower end of the electrode nozzle that performs a rotativemovement, while the electrode nozzle itself is not rotated. In suchmanner, the electrode nozzle can be cooled with water easily, while itbecomes possible to make a more extensive application of the presentwelding device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(A) and (B) are a cross-sectional side view showing a rotativearc welding device according to a preferred embodiment of the presentinvention, and a plan view of a gear section for transmitting rotativemovement to the lower end of the electrode; and FIG. 2 is a schematiccross-sectional side view showing the conventional rotative arc weldingdevice.

BEST MODE FOR WORKING THE INVENTION

A preferred embodiment of the present invention will be described byreferring to the drawings.

FIGS. 1(A) and (B) are cross-sectional side views of a rotational arcwelding device according to a preferred embodiment of the presentinvention and a plan view showing a gearing unit for imparting arotative motion to the electrode.

Referring to FIG. 1, the numeral 20 denotes an electrode, the numeral 21a welding wire, the numeral 22 a rotary electric motor, the numeral 23 ashaft of the motor 22, and the numeral 24 a gear secured to the shaft 23and excited into a high-speed rotation by the motor 22, and the numeral25 a gear excited into a high-speed rotation by the gear 24. The numeral26 denotes a self-aligning bearing adapted for supporting the electrode21 and attached to the gear 25 with an offset of a predetermineddistance d from the center of the gear 25 so that the electrode 21 willbe rotated at an elevated speed by rotation of the gear 25. The numeral27 denotes a self-aligning bearing acting as a supporting point for therotating electrode 21. The numeral 28 denotes a gear box attached to arack of a welding dolly, not shown. The numeral 29 denotes a powersupply cable for supplying an electrical power to the electrode. Thenumeral 30 denotes a welding arc, the numeral 31 a work to be welded andthe numeral 32 an adjustment unit for adjusting the rotative diameter.The numeral 33 denotes an attachment opening for a power supply cableterminal and the numeral 34 a bearing for supporting the gear 25.

The lower end of the electrode 21 is excited into a rotative movementthrough the gear 24 by the motor 22 with the self-aligning bearing 27 asa support point. In this manner, the welding arc 30 and the foremostpart of the welding wire 21 supplied at the lower extremity of theelectrode 20 perform a rotative circular motion on the work 31. Thediameter of rotation D at the end of the rotating welding wire 21 may beadjusted by changing the distance at the adjustment unit 32. Since theelectrode 20 itself is not turned when the lower end of the electrode 20performs a rotative movement, it is possible to supply the currentdirectly to the electrode 20 through the feeder 29 as shown.

It will be noted that FIGS. 1(A) and (B) merely illustrate a preferredembodiment of the present invention without limiting the presentinvention to such specific embodiment. For example, the self-aligningbearing 27 used as the fulcrum or supporting point for the electrode 20may be replaced by a spherical bearing since the movement of the portionof the electrode 20 is small. Also it is to be noted that any othertransmission system than the gear shown in the above embodiment may beused as the transmission system from the motor 22 to the gear 25. Thewelding method to which the present invention is applied is the weldingmethod as a whole.

We claim:
 1. A rotative arc welding device comprising:first supportingmeans for supporting an upper portion of an electrode as the supportingpoint of a circular conical motion; second supporting means forsupporting a middle portion of said electrode with an offset of apredetermined distance from a center of a disk; driving means fordriving said second supporting means to make a lower end of saidelectrode travel in a circular orbit; and adjusting means for adjustingthe distance between said first supporting mens and said secondsupporting means, thereby adjusting the diameter of said circular orbitof the electrode.
 2. A rotative arc welding device according to claim 1wherein the upper portion of the electrode is supported by aself-aligning bearing.
 3. A rotative arc welding device according toclaim 1 wherein the upper portion of the electrode is supported by aspherical bearing.
 4. A rotative arc welding device according to claim1, wherein the center portion of the electrode is supported by aself-aligning bearing and said driving means comprising a rotativelydriven gear, said self-aligning bearing being mounted on said gear withan offset of a predetermined distance from the center of said gear.